+0  
 
0
121
2
avatar

Thanks!

Guest Feb 22, 2018
edited by Guest  Feb 22, 2018
 #1
avatar+88899 
+1

Due to symmetry  the x coordinate of the vertex = 5

 

The points  (3,0) (7,0) and (2, - 5)  are on the graph

 

And we have this form

 

y  =  ax^2 + bx + c

 

The x coordinate of the vertex  =  

 

-b / (2a)  =  5

-b  = 10a

b  =  -10a

 

So we have that using  (3,0)

 

0  =  a(3)^2 - 10a(3)  + c

0 =  9a - 30a + c

0  =  - 21a + c

-c = -21a

c = 21a

 

And using  (2, -5)

-5  =  a(2)^2  - 10a(2) + 21a

-5  = 4a - 20a + 21a

-5  = 5a

a  =  -1

 

And b =  -10(-1)  =  10

And c = 21(-1)  = -21

 

So our function is :

 

y = -1x^2 + 10x  - 21

 

Here;s the graph : https://www.desmos.com/calculator/u2qnb8dswx

 

 

cool cool cool

CPhill  Feb 22, 2018
 #2
avatar
0

Thanks so much!

Guest Feb 22, 2018

6 Online Users

New Privacy Policy

We use cookies to personalise content and advertisements and to analyse access to our website. Furthermore, our partners for online advertising receive information about your use of our website.
For more information: our cookie policy and privacy policy.